Coagulometer capsule

ABSTRACT

A TWO PIECE TUBULAR CAPSULE FOR CONDUCTING COAGULATION TESTS ON BLOOD AND OTHER LIQUIDS HAVING THREE SEPARATE CHAMBERS, THE FIRST TWO COMMUNICATING WITH EACH OTHER, DEFINED BY TWO FRANGILBE MEMBRANES AND A SOLID DISC. A SHAFT HAVING A RECESSED STIRRING END IS ATTACHED TO THE FIRST MEMBRANE AND COOPERATES WITH A STIRRING SLUG ATTACHED TO SAID SECOND MEMBRANE. THE SHAFT IS MOVED AXIALLY TO BREAK THE SECOND MEMBRANE AND MIX THE LIQUIDS IN EACH CHAMBER. THE SHAFT IS THEN ROTATED RELATIVE TO THE BODY OF THE CAPSULE TO STIR THE MIXED LIQUID TO DETERMINE THE COAGULATION TIME OF THE SAMPLE LIQUID BEING TESTED.

Sept. 19, 1972 c SANZ COAGULOMETER CAPSULE 2 Sheets-Sheet 1 Filed March 17, 1970 United States Patent 4,124 69 Int. Cl. G01n 11/14, 33/16, 33/26 US. Cl. 23-253 R 22 Claims ABSTRACT OF THE DISCLOSURE A two piece tubular capsule for conducting coagulation tests on blood and other liquids having three separate chambers, the first two communicating with each other, defined by two frangible membranes and a solid disc. A shaft having a recessed stirring end is attached to the first membrane and cooperates with a stirring slug attached to said second membrane. The shaft is moved axially to break the second membrane and mix the liquids in each chamber. The shaft is then rotated relative to the body of the capsule to stir the mixed liquid to determine the coagulation time of the sample liquid being tested.

This invention provides a device for carrying out a blood test and a method of operating this device.

The coagulation of human blood is the result of a process of a particularly complex biochemical nature which calls into play a dozen components called factors, conventionally denoted by means of Roman numerals I, H, III, etc.

The absence or deficiency of one or more of these factors causes, in the human body, the coagulation of the blood to deteriorate or even to become impossible in certain cases and almost always causes more or less acute ailments in certain parts of the body, in particular the liver, as well as certain defects in the metabolism.

The detection of the factors which may be deficient or absent in blood is clearly very important, whether it be for the purpose of deciding the most appropriate treatment for eliminating or circumscri-bing certain ailments that may have been observed in a subject, or as a precautionary measure, before any surgical operation, for avoiding, for example, haemorrhages.

This detection is also of particular importance in respect of the treatment to be given to patients suffering from a thrombosis and to whom it is necessary to administer anticoagulants in a quantity which must clearly be determined after taking into account the abnormal factors which were the cause of the thrombosis.

Among the numerous tests which are performed to carry out this detection, that proposed by A. Quick is one of the simplest and swiftest to make. This test which is essentially intended to show up any concentration deficiency of the factors I, II, V, VII and X of the blood, is broadly speaking carried out in the following manner: after adding a solution of anticoagulant (solution of trisodium citrate or sodium oxalate) to freshly drawn blood, thereby removing from the blood the Ca++ ions (factor IV) and preventing coagulation thereof, the mixture is subjected to a centrifugal operation and the plasma which comes to float is drawn off. To this floating plasma is then added an equal quantity of a suspension of thromboplastine (a tissue extract of a kind corresponding to that of factor III of the blood) and the mixture is brought to a temperature of 37 C. Into this mixture is then introduced a solution of calcium chloride (to add Ca++ ions), also brought to 37 C.,

and the coagulation time of the resulting composite liquid is measured.

According to one variant of this test, proposed by Soulier, it is possible to replace the floating plasma by natural freshly drawn blood.

If the concentration of the factors I, II, V, VII and X of the tested blood is normal, the coagulation time is of the order of 10 to 15 seconds, according to the activity of the thromboplastine used. On the other hand, a coagulation time greater than the value obtained with normal blood indicates a deficiency of one or more factors without, however, indicating which one; other kinds of tests enable these factors to be identified.

The measurement of this coagulation time, originally effected by means of a simple chronometer which an operator stopped in an empiric manner, on the basis of a visual estimation of the state of coagulation reached by the composite liquid under examination, has for some time been carried out automaticaly by means of various forms of apparatus capable of measuring the time necessary for the formation of a clot in the composite liquid.

Although such apparatus have helped to improve the accuracy of coagulation time measurements, and to accelerate, to some extent, the performance of Quick or Soulier tests as such, these tests still are however, a relatively complex operation, notably as regards their preparation which requires delicate manipulations, in particular liquid metering operations, requiring fairly substantial equipment and also qualified personnel.

An object of the present invention is to obviate the above mentioned disadvantages.

'It is a further object of this invention to provide a viscosimeter capsule wherein thrombokinase can be employed without problems of its instability being encountered.

Another object of this invention is to provide a viscosity testing capsule wherein sodium citrate or oxalate and thrombokinase are combined within one chamber thereof.

Another object of this invention is to provide a blood coagulation testing capsule wherein a blood sample may be indefinitely stored prior to a coagulation test.

A further object of this invention is to provide a capsule for containing a blood sample and the necessary solutions for determining the coagulation time of said sample.

The device provided by the present invention comprises a first enclosure containing a suspension of at least one blood coagulation factor in a solution of a blood anticoagulant and intended to receive a metered quantity of blood to be tested, a second enclosure containing a solution of a calcium salt, a passage connecting said first and second enclosures, and removable means for closing off said passage.

As for the method of operating this device, it comprises introducing a metered quantity of blood into said first enclosure, heating the contents of both enclosures to a temperature of 37 C., removing said closing-off means to cause the contents of said first enclosure to mix with the contents of said second enclosure, and measuring the time taken by the resulting mixture to acquire by coagulation a predetermined degree of viscosity.

In the accompanying diagrammatic drawings:

FIG. 1 is a vertical section through one form of embodiment of the device provided by the invention;

FIGS. 2, 3 and 4 are cross-sections along lines II-II, IIIIII and IVIV, respectively, through the device illustrated in FIG. 1; a

FIGS. 5, 6 and 7 illustrate three successive phases of one method of operating the device illustrated in FIG.

1; and

FIGS 8, 9 and 10 are views similar to those of FIGS. to 7, and show a second method of operating the device illustrated in FIG. 1.

The device shown in FIGS. 1 to 4 comprises two tubular elements 1 and 2, of plastic material, for example polyethylene or polypropylene, secured to one another by interengagement. In a preferred embodiment, this device has a total length of about 2.5 cm. and an external diameter of about one centimeter.

The internal surface of element 1 is smooth over a first wall portion 1a and is formed with longitudinal ribs or flow impedance means over a second wall 1b, which is a continuation of the first and which is separated therefrom by an intermediate flange or ridge of triangular section. This flange is secured, via a weak annular membrance 1d, to a frusto-conical stud 3a formed at the lower end of a rod 3 which is disposed inside element 1, co-axially therewith, and which extends to near the upper opening of this element. As can be seen, the portion 3b of rod 3, adjacent the stud 3a, has four faces and is of square cross-section. In addition, a cylindrical recess 30 is formed in the underface of stud 3a.

The tubular element 2 is formed, on its internal surface, with a flange 2a or ridge of triangular section separating two adjacent wall portions 215 and 20 which are provided with internal ribs 211 or flow impedance means having a section and distribution similar to those of the ribs on wall portion 1b of element 1. To the flange 2a there is secured, via a weak annular membrane 2d, a disc 4 or slug having a frusto-conical edge and from the upper face of which projects a cylindrical peg 4a having a height greater than the depth of the recess 30 in rod 3 but slightly less than the axial length of the wall portion 211 of element 2; the diameter of peg 4a is less than that of the recess 3c and its upper end is rounded. Peg 4a forms a gauge for measuring a quantity of blood being metered for testing, as will be explained later.

Stud 3a and wall portion 1b of element 1 define within the latter a chamber L Similarly, disc 4 and Wall portion 21) of element 2 define in the latter a chamber L When elements 1 and 2 are in interengagement, wall portions 1b and 2b together define a single enclosure E (FIG. 5).

Below wall portion 20, the internal surface of element 2 is cylindrical over a small length to form a seat 22 for a disc 5 force-fitted thereinto and abutting against the lower end of ribs 2h.

The disc 4 or slug, the wall portion 20 of element 2 and the disc 5 define within element 2 an enclosure E (FIGS. 1 and 5).

Below the disc 5, element 2 includes a wall portion formed with an internal surface which flares frusto-conically outwards at 21 followed by a cylindrical wall portion 2g, the diameter of the opening of this element at the level of the wall portion 2g being greater than the diameter of any other part of the opening of the device.

Enclosure E is partially filled with a suspension of a blood coagulation factor in a solution of blood anticoagulant. This could for instance be a suspension of thromboplastine in a solution of trisodium citrate. With a device having a length of 2.5 cm. and a diameter of 1 cm., the total amount of suspension required would be 20 1., the trisodium citrate being titrated at 0.87 g./ 100 ml. (0.025 mole).

In enclosure E there is introduced an equal quantity of calcium chloride solution, i.e. 20 l. with a device of the indicated size, this solution being titrated at 0.416 g./ 100 ml. (0.0375 mole). The above two solutions are therefore chemically equivalent since citrate is trivalent and calcium is bivalent.

The volume of enclosure E is equal to at least double the volume of the thromboplastine suspension since, in order to carry out the test, this enclosure is also intended to receive a quantity of blood equal to that of the suspension, i.e. equal to 20 ,ul. in the example being considered.

As is known, any calcium chloride solution is particularly stable and can thus be kept for a relatively long period of time; the same applies to any trisodium citrate solution.

Such, however, is not the case with thromboplastine which, as is known, can only be kept, in suspension form, if it is mixed with a stabilising liquid, e.g. a polyalcohol.

It is also known that to prevent blood from coagulating it is essential to remove therefrom the Ca ions; this can, for instance, be done by mixing the blood with trisodium citrate, as already indicated, or by way of variant, with sodium oxalate.

It has now been found that trisodium citrate and sodium oxalate are also excellent tbromoboplastine stabilisers so that the above described device can, once ready for use, be stored for a relatively long period of time in cool surroundings, say about 4 C., even after having introduced the blood to be tested into enclosure 13,, the blood being prevented from coagulating since the above sodium compounds will have fixed the Ca++ ions that are contained in the blood.

In practice, the described device is supplied already filled with its CaCl and thromboplastine suspension contents in the above indicated quantities, and preferably wrapped in lagging.

To perform a coagulation test, first the blood must be introduced into enclosure E and in particular into the portion L thereof. For this, the device is placed upside down in relation to the position illustrated in FIG. 1 and is subjected to abrupt downward acceleration so as to clear space L of any thromboplastine suspension in trisodium citrate solution.

To enable a user easily to determine which of elements 1 and 2 is occupying the lower position prior to performing this operation, element 1 is provided on its outer surface with an identification mark such as for instance a coloured stripe near one of its ends. By way of variant, element 1 could be made of plastics material having a colour which contrasts with that of the material used to make element 2.

Elements 1 and 2 are then separated and the blood to be tested, generally freshly drawn blood, is put into space L in a quantity such that the top surface of the blood lies substantially at the level of the tip of peg 4a, this quantity amounting to 20 ,ul. in the case of the described device. It should be noted that the blood surface will not be plane but slightly bulging because of surface tension.

Elements 1 and 2 of the device are then assembled again and the assembled set-up is then shaken, for instance by an axial movement, so as intimately to mix the blood with the suspension of thromboplastine in trisodium citrate solution, thereby fixing the Ca++ ions of the blood by means of the trisodium citrate and hence preventing the blood from coagulating.

At that point either the device can be stored at low temperature for later completion of the test to determine the blood coagulation time or the test can be completed immediately. In the first case, the blood may for instance be collected at one place and the remainder of the test can be carried out at another, which may be geographically far apart from the first, since the blood once collected will not coagulate in the device.

To find out the coagulation time of the blood being tested, the contents of the device are heated to a temperature of 37 C. by placing the device for a sufficiently long period of time in an atmosphere having that temeprature. The device is then fitted over a locating boss 7 of cylindrical shape (FIGS. 5 to 7) projecting from base 6, the diameter of boss 7 being slightly less than that of that part of the opening in element 2 surrounded by wall portion 2g and its height being slightly greater than the distance between the bottom end of element 2 and the underside of disc 5. As shown, boss 7 is also bevelled along its top edge,

this annular bevel having an inclination and an area corresponding substantially to the inclination and area of the flared surface 2] inside element 2.

The top end of rod 3 has then fitted thereon a cap 9 secured to the end of a pin 8 in coaxial alignment with rod 3 and having a sharp point 8a. A force F is exerted on pin 8 such that point 8:: may be driven into rod 3 (FIG. 5) and such as to cause ripping of membrane 1d. Rod 3 then is driven into enclosure E thereby causing the recess 30 in stud 3a to fit over the peg 4a of disc 4 (FIG. 6), whereupon membrane 2a is caused to rip, thereby causing disc 4 and rod 3 to enter enclosure E (FIG. 7).

As a result the mixture of blood and of thromboplastine suspension in trisodium citrate solution that is contained in enclosure E comes into contact with the calcium chloride solution contained in enclousre E Since this latter solution is chemically equivalent to the trisodium citrate solution, it is therefore able to restore to the blood a number of Ca++ ions equivalent to the number of Ca++ ions that were removed therefrom by the trisodium citrate upon bein introduced into enclosure E The blood contained in the device begins to coagulate and what is now required is to measure the coagulation time. This is in fact achieved by measuring the time taken by the liquid mixture contained in the device to reach a certain predetermined viscosity value.

Thus, as soon as the liquids in enclosures E and E are mixed together as described, pin 8 is rotated, e.g. in direction F (FIG. 7), and the time that elapses between the moment rotation begins and the moment when the resistance exerted on rod 3 under the action of viscosity reaches a predetermined value is then measured, this predetermined value being characteristic of a particular state of coagulation reached by the blood being tested. With normal blood, this time is of the order of about 10 to seconds depending on the activity of the thromboplastine being used.

This detection can be done in numerous ways. For instance, either there can be effected a dynamometric measurement of the change that takes place in time of the torque acting on pin 8 or there can be effected a tachometric measurement of the change that takes place in time of the speed at which pin 8 rotates when the driving torque remains constant, or else there can be effected a measurement of the change that takes place in time of the power needed to drive pin 8 to keep its rotational speed constant. It is also possible to drive pin 8 through the intermediary of a calibrated clutch set for disengagement when the resistive torque acting on pin 8 reaches a critical value corresponding to a desired state of blood coagulation, and to measure the time that elapses between the moment when pin 8 begins to rotate and the moment when the clutch disengages.

The blood coagulation time can also be determined by operating the described device in a manner slightl different from the one described. This alternative method of operation is illustrated by FIGS. 8 to 10. Here, the device is fitted onto a mandrel 10 having a bevelled top edge 10a which comes to bear against the flared surface 2 inside element 2. Mandrel 10 is adapted to move vertically between a first, lower, position, shown in FIG. 8, and a second, upper, position, shown in FIG. 10, rod 3 being kept stationary, both angularly and axially, by means of a fixedly mounted pin 8 in coaxial alignment with the mandrel 10 and in engagement with rod 3 by means of a point 8'0.

As will be observed from FIGS. 8 to 10, the ripping of the membranes 1d and 2d in this instance is caused by axial movement of the device under the action of a thrust exerted by the mandrel in direction F such movement causing first membrane 1d (FIG. 9') and then membrane 2d (FIG. 10) to tear.

To measure the coagulation time of the blood being tested, pin 8 is kept angularly stationary, mandrel 10 is rotated for instance in direction F and the increase in viscosity that isundergone by the liquid mass contained in the device is measured, such increase being due to coagulation of the blood. This detection can be done by any one of the ways outlined above in relation to FIGS. 5 to 7.

I claim:

1. A capsule adapted to receive a liquid sample and solutions for testing the viscosity of said sample, said capsule comprising first and second hollow members, said members each being configurated on one end to interengage one with the other, said first member having a first frangible partition means therein adjacent said configurated end, the hollow area between said first frangible partition means and said configurated end forming a first chamber means, said second member having a second frangible partition means adjacent said configurated end, the hollow area between said second frangible partition means and said configurated end forming a second chamber means, a third partition means in said second member spaced from said second frangible partition means, the area between said second frangible partition means and said third partition means forming a third chamber, said first, second and third chamber means having flow impedance means therein, said chamber means adapted to receive a sample liquid and other solutions therein, an agitating means associated with one of said members and adapted to agitate said mixture of said sample liquid and other solutions to determine the viscosity of said liquid, whereby said liquids and solutions are mixed upon rupture of both said frangible partition means.

2. A capsule as in claim 1 wherein said agitating means is attached to said first frangible partition means and is adapted to rupture said first and second frangible partition means when said members are interengaged.

3. A capsule as in claim 2 wherein said agitating means comprises a shaft extending lengthwise within said first member and attached at one end to said first frangible partition means, said attached end being truncated in profile with said first partition means being attached to said truncated edge, and shaft being adapted to be first moved axially toward said second member to rupture said frangible partitions and then to be rotated to stir said liquids and other solutions until coagulation occurs.

4. A capsule as in claim 3 including a slug means, said slug means being attached to said second frangible partition, means, a projection on said slug means extending toward said first member, a recess in the truncated end of said agitating shaft adapted to fit over said projection when said agitating shaft is propelled axially toward said second member to rupture said first and second frangible partition means.

5. A capsule as in claim 1 wherein said first and second members are tubular in cross section.

6. A capsule as in claim 1 wherein said first and second partition means comprise thin membranes separating said chamber means.

7. A capsule as in claim 6 wherein there are annular ridges around the inner surfaces of said members, said membranes being attached to said ridges.

'8. A capsule as in claim 6 wherein said agitating means is attached to one of said membranes and adapted to be moved axially to sever said membranes to allow said sample liquid and other solutions to intermix prior to subjecting them to realtive rotation between said agitating means and said two members to determine the viscosity of said sample liquid.

9. A capsule as in claim 1 wherein said flow impedance means comprise longitudinal grooves in the walls of all of said chamber means, said grooves tending to aid in coagulating the combined mixture of said sample liquid and other solutions when said mixture is stirred by said agitating means.

10. A capsule as in claim 1 wherein said third partition means comprises a separate disc, said disc forcefitted into said second member.

11. A capsule as in claim 1 wherein said agitating means comprises an agitating shaft attached to said first frangible partition means, said flow impedance means consisting of longitudinal grooves in the inner surfaces of said chamber means whereby said agitating shaft is adapted to be thrust axially in the direction of said second member to rupture said frangible partitions and mix said sample liquid and other solutions, and whereby said grooves are adapted to cooperate with said agitating shaft to coagulate said mixture upon relative rotation between said agitating shaft and said grooves.

12. A capsule as in claim 1 wherein said one of said members has a flange means on one end thereof and said other member has a reduced portion on one end thereof, said flange means and reduced portion cooperating to fit said members together.

13. A capsule as in claim 1 wherein an agitating member is associated with said first frangible partition means and said second member has means thereon adapted to connect it with a rotating member whereby, after rupture of both said frangible partition means and mixture of said sample liquid and other solutions, said members are rotated relative to said agitating member and, in conjunction with said flow impedance means assists the coagulation of said mixture.

14. A capsule for receiving a liquid sample and other solutions to test the coagulation time of said sample, said capsule containing first, second and third chamber means, in that order, a first frangible partition means defining said first chamber means, a second frangible partition means separating said first and second chamber means, an agitating means connected to said first frangible means and adapted, upon movement toward said second chamber means, to rupture said first and second frangible partition means, projection means annularly spaced around the first and second chamber means and adapted to cooperate with said agitating means to cause the resulting mixture of said sample and other liquids to coagulate.

15. A capsule as in claim 14 wherein said capsule consists of two interengaged housings, the first housing containing said first chamber means and the second housing containing said latter two chamber means.

16. A capsule as in claim 14 wherein said agitating means comprises a plunger axially movable with respect to said capsule.

17. A capsule as in claim 16 wherein said projection means compirses a series of spaced annular ridges located within at least two of said chambers, the plane of said ridges being substantially normal to the direction of said plunger.

18. A capsule as in claim 14 wherein said capsule means is tubular and comprises two housings, said first chamber means located with the first housing and second and third chamber means located within said second housing.

19. A capsule as in claim 14 wherein said agitating means comprises an elongated shaft attached to said first frangible partition means and adapted to be driven axially toward said second housing to rupture said first and second frangible partition means to allow said liquid sample and other solutions to mix.

20. A- capsule as in claim 19 wherein said first and second frangible partition means consist of thin membranes attached around their outer edges to the inner surfaces of said housings to define said chambers.

21. A capsule as in claim 20 wherein said elongated shaft has a truncated end portion facing said second housing, the edges of said truncated portion being attached to first membrane, the remainder of said elongated shaft being polygonal in cross-section.

22. A capsule as in claim 21 including a circular slug mounted in the middle of said second membrane, said slug having a projection extending toward said first housing, and said elongated shaft having a recess in its end face adapted to loosely fit over said projection when it is moved axially to rupture said membrane, said slug projection adapted to act as a guide during the filling of said second chamber.

References Cited UNITED STATES PATENTS 3,521,745 7/ 1970 Schwartzman 206-47 A 3,190,731 6/1965 Weiskopf 23-292 3,560,162 2/1971 Mitlcman 23253 2,982,396 5/ 1961 Shihadeh 20647 A JOSEPH SCOVRONEK, Primary Examiner US. Cl. X.R. 

